1. Field of the Invention
This invention pertains to the field of bio-affecting compositions; more specifically, it pertains to such compositions containing organic active ingredients comprising the insecticide methomyl and certain esters of 2-dihalovinyl-3,3-dimethylcyclopropane carboxylic acids, the latter being pyrethroid insecticides related to chrysanthemum acid, and to the use of the compositions for controlling insects.
2. Description of the Prior Art
New pyrethroids, insecticidal 2-(2,2-dihalovinyl)-3,3-dimethylcyclopropanecarboxylates [Elliott, et al., Nature, 246, 169 (1973); British Pat. No. 1 413 491], are of great interest currently because, unlike previous compounds of this type, such as natural pyrethrins and the older synthetic pyrethroids (for example, allethrin and tetramethrin) they have good photo-oxidative stability. However, the new pyrethroids are very costly, and ways to increase their cost effectiveness are actively being sought.
Synergists have been used commercially in combination with pyrethrins and the older pyrethroid insecticides because they lessen the amount of insecticide required and thus reduce the cost at which insect control is achieved. Some of the most widely used synergists for pyrethrins and the older pyrethroids display little or no insecticidal activity in their own right; for example, the commercially important piperonyl butoxide [U.S. Pat. No. 2,550,737] and certain phosphonates such as mono(alkyl and alkenyl) mono-.omega.-alkynyl arylphosphonates [U.S. Pat. Nos. 3,885,031 & 3,944,666].
Some of the compounds which produce synergistic combinations with the new pyrethroid, 3-phenoxybenzyl 2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylate, are themselves insecticides. It is known that combinations of 2-allyl-3-methylcyclopent-2-en-1-one-4-yl 2-(2,2-dimethylvinyl)-3,3-dimethylcyclopropanecarboxylate (allethrin) and N-(3,4,5,6-tetrahydrophthalimido)methyl 2-(2,2-dimethylvinyl)-3,3-dimethylcyclopropanecarboxylate (tetramethrin) with the aforesaid insecticidal 2-dihalovinyl-3,3-dimethylcyclopropanecarboxylate exhibit synergism when used to control several insect species, including insects of the order Diptera [U.S. Pat. No. 3,899,586]. O,O-Dimethyl 0-(3-methyl-4-nitrophenyl) phosphorothioate (fenitrothion) and 1-naphthyl methylcarbamate (carbaryl), in combination with the aforesaid insecticidal 2-dihalovinyl-3,3-dimethylcyclopropanecarboxylate, exhibit synergism when applied to Nephetettix cinctceps, a rice pest [Japan Kokai 75 58,237 and 75 64,422, respectively].